Display fountain, system, array and wind detector

ABSTRACT

A fountain ( 50 ) comprises a supply of water under pressure, a primary fluidic diverter ( 10 ) having an input ( 12 ) for said supply, and first and second outputs ( 16   a, b ) diverging from said input. Two control ports ( 20   a, b ) are provided with control flow to direct input flow to one or other of the two outputs that lead to the two inputs of a vortex amplifier ( 40 ). This comprises a vortex chamber ( 54 ), a radial port ( 50 ), a vortex inducing port ( 60 ) and an axial output port ( 58 ). One ( 16   a ) of the diverter outputs is connected to the vortex inducing port, the other ( 16   b ) to the radial port, so that supply to said axial output port is modulated by formation of a vortex in the chamber when flow is to the vortex inducing port. The axial port leads to a nozzle whereby a vortex spray or axial jet is produced, depending on which diverter output ( 16   a, b ) is active. A wind detector ( 100 ) has a vertical jet ( 102 ) and a catcher ( 104 ) which fails to catch water from the jet in high wind conditions. The catcher feeds the control port ( 20   a ) of a diverter  10   1 , or such other pressure or flow detector as may be convenient. A fountain array of elements may comprise a number of diverters, the outputs of which have branches supplying the control ports of others in the array, whereby internal control is provided.

The present invention relates to fountains, particularly displayfountains, although the invention in its different aspects may also haveother applications.

Display fountains come in many shapes and sizes. Water “features” are acommon and increasingly popular aspect of domestic garden scenery.Larger displays are frequently employed in public places and have longbeen an adjunct to architectural or sculptural works. Most fountains arestatic, in that they have a single mode of operation—they are either on,or off. Static fountains are the simplest and least expensive, andgenerally only require a pump or water supply to operate. These kindsare affordable by most people and are seen in many garden ponds. Variousnozzles provide different effects from sprays to jets, and may bearranged to entrain air so that a foaming spray is generated.

However, more sophisticated fountains are dynamic in that theiroperation is controlled, and accordingly varied, by different jets beingswitched on or off, or having their pressures varied, or redirected. Thecontrol arrangement is invariably electronic with greater or lessercomplication, and involves the use of selectively operable mechanicalvalves that can interrupt flow, as may be desired. By this means a widevariety of different effects can be achieved. But such variety comes ata significant cost, not just in terms of price, but also of reliability.Fountains generally involve recycling pond or fountain pool water, anddebris eventually builds up and can block valves etc.

One recent development in fountain displays is the use of slugs ofwater. Although a continuous jet of water involves continuous motion,this fact disguised by a complete arc of a water jet, which can appearsomewhat static. If, however, slugs of water are generated, which slugshave a beginning and an end, the motion is brought home to the viewer.U.S. Pat. No. 5,979,791 and U.S. Pat. No. 6,119,955 both disclosearrangements for producing slug jets, one involving the use of asyringe-type of arrangement, and the other involving a plug rapidlyreleasing and closing an orifice of a chamber containing liquid underpressure.

U.S. Pat. No. 5,918,809 discloses a water display arrangement in which afloat is provided with nozzles supplied by flexible water pipes, thereaction from the nozzles moving the float about on a pond or poolsurface and creating interesting effects. However, mechanical switchingarrangements are provided.

Numerous patents disclose fluidic arrangements for producing oscillatingjets, whose main application appears to be in the automotive field forvehicle windscreen and headlight washing. Examples are to be found inU.S. Pat. No. 6,253,782, U.S. Pat. No. 5,213,269, U.S. Pat. No.5,181,660, EP-A-0208174 U.S. Pat. No. 4,398,664, U.S. Pat. No. 452,867and WO-A-7900361.

EP-A-0331343 discloses the use of a fluidic bistable oscillator in theproduction of a spray of droplets having a narrow size spectrum.SU-A-478622 discloses a display fountain using a diverter to providealternating jets under pneumatic control.

It is an object of the present invention to provide a display fountainthat has opportunities for a variety of functions without the necessityof moving valves, pistons or the like mechanical components.

In accordance with a first aspect of the present invention there isprovided a fountain comprising:

a supply of water under pressure;

-   -   a primary fluidic diverter having an input for said supply, and        first and second outputs diverging from said input, two control        ports provided with control flow to direct input flow to one or        other of said outputs; and    -   a vortex amplifier comprising a vortex chamber, a radial port, a        vortex inducing port and an axial port; wherein one of said        first and second primary diverter outputs is connected to said        vortex inducing port and the other is connected to said radial        port, said axial port leading to a nozzle whereby an alternating        vortex spray or axial jet is produced. Accordingly, when the        diverter switches flow to the vortex inducing port of the vortex        amplifier, a vortex is induced in the vortex chamber so that        flow issuing from the nozzle swirls and forms a conical spray.        However, when the diverter switches flow to the radial port of        the vortex amplifier, no vortex forms in the vortex chamber, the        flow therein being only radial, whereby a non-swirling axial and        coherent jet issues from the nozzle.

Preferably, said control ports are interconnected by an inertia loop,whereby oscillations are induced in the control flow to switch flowalternately between said first and second outputs.

Alternatively, said outputs may have restrictors therein and includefeed back loops into said control ports, whereby oscillations areinduced in the control flow to switch flow alternately between saidfirst and second outputs.

Said first and second outputs of either diverter may be vented toisolate each input from the outputs, and the outputs from one another.

Any of said diverters may be cusped between said first and secondoutputs to increase stability of flow through said first and secondoutputs.

Preferably, said vortex amplifier comprises an annular chamber formed bya tubular housing and central body, supply flow to the amplifierentering said annular chamber at one end, the other end of the annularchamber being terminated by a nozzle plate defining with said centralbody said vortex chamber, said housing having an opening forming saidvortex inducing port.

Said vortex inducing port is preferably a passage from a supply chamberoutside said housing and arranged tangentially with respect to saidvortex chamber. Alternatively, said vortex inducing port comprises aplurality of said openings in said housing, each opening provided with avane to tangentially direct radial inflow from a supply chambersurrounding said housing.

Preferably, said nozzle is interchangeable with different nozzlesdisplaying one of various spray patterns when vortex spray issuestherefrom.

A spray catcher may be disposed beyond the nozzle to deflect vortexspray issuing from said nozzle, the catcher having an orifice to permitpassage of said axial jet to flow unimpeded. Indeed, the catcher may beformed as an inverted cup, so as to destroy entirely said vortex spray,although still permitting the jet flow.

Alternatively, said nozzle may open into an annular diffuser to catchsaid vortex spray, but not said axial jet, said diffuser opening into anannular pressure plenum. The plenum may be provided with discrete nozzleexits. These can produce discrete jets and they may be spaced around thecentral jet to produce a crown-like spray, alternating with the central,axial jet. On the other hand, the nozzle exits may be employed forswitching of other elements of a fountain system.

Two vortex amplifiers may be provided in parallel, each with its ownsupply to its radial port, each vortex inducing port being connected toone or other of said first and second outputs of the primary diverter.

Indeed, such an arrangement may also be provided as a component of afluidic control arrangement in a fountain system wherein, instead ofsaid axial outputs of the two vortex amplifiers leading to nozzles, theylead to further components of the system, and which are arranged to becontrolled by greater or lesser flow rates from the vortex amplifiersthat issue from said axial output depending on whether there is flowinto said vortex inducing port.

Alternatively, or in addition a fountain system may include two primarydiverters whose first outputs are joined together and comprise theradial input for said vortex amplifier, and whose second outputs areconnected to separate vortex-inducing ports of said vortex amplifier,whereby several modes of operation of the vortex amplifier results. Toachieve variety in the display, the diverters are preferably arrangeddeliver flow at different strengths, either by being different in sizeor of supplied pressure and/or flow. The diverters could be designated“strong” and “weak”. For example, when the vortex inducing ports arearranged to induce a vortex in the same direction with respect to oneanother, then column A in the following table shows the resulting flowstates in the axial outlet of the vortex amplifier. The first twocolumns indicate the direction in which the diverters are switched (tofirst or second outputs). Four possible circuit states are produced,ranging from one (first row) with zero swirl (and a strong coherent jet)to one with maximum swirl (fourth row, with both diverters inducingvortex flow). The others have intermediate swirl strengths (partialswirls 1 and 2 being different) giving a total of four possible waterjet or spray effects.

Alternatively, if the vortex inducing ports are arranged to oppose oneanother, then the four possible flow states are as tabulated in columnB. They range between zero swirl (row 1) and a high swirl state (rows 2or 3 depending on the relative strengths of the diverter flows). Thishigh swirl state has less swirl intensity than that of column A. Thefourth row, corresponding to both diverters attempting to induce vortexflow in opposite directions produces another intermediate swirl state.Consequently this “contra-swirl” configuration produces a finergradation of swirl intensity than that with co-directional vortexinducing ports. Small degrees of swirl cause great degrees of effect inthe jet efflux. The relative swirl strengths of the partial swirl statesdepend on the relative strengths of the two diverters but thisrelativity or ranking is unimportant. The significant attribute is theability to produce four distinct display phenomena. TABLE I Diverter 1,Diverter 2, 1.1.1A 1.1.2B Output in Output in Axial output from Axialoutput from flow flow Vortex amplifier Vortex amplifier First FirstNon-swirl flow Non-swirl flow Second 2. First Partial swirl 1 Partialswirl 1 First Second Partial swirl 2 Partial swirl 2 Second SecondMaximum swirl Partial swirl 3

If the diverters are themselves controlled to switch at different times,the period of each phase can vary and appear somewhat random. This canbe achieved, for example, by a control loop for each diverter having adifferent length, given that it is primarily the length of such loopthat controls oscillation period.

A novel form of self oscillating vortex nozzle having potentialapplication in a fountain system according to the first aspect of thepresent invention comprises a cylindrical vortex chamber having acentral output nozzle and an input comprising a section of thecylindrical wall of the chamber to which an input chamber is connected,a narrowing of the input chamber being provided at the input section ofthe vortex chamber, whereby flow entering the vortex chamber oscillatesbetween swirling entry and straight radial entry leading to oscillationsin the out put between a straight jet and a swirling spray.

Windy conditions adversely affect the appearance of fountains, andfrequently causes loss of water from a surrounding pool, which might beproblematic in respect both of the loss of water from the pond or pool,as well as wetting surrounding areas.

Consequently, in its first aspect, the invention also provides a winddetection and adjustment device comprising a catcher for water issuingfrom a detecting jet and falling under no-wind conditions, and a windcontrol diverter having a supply input, first and second wind controloutputs diverging from said supply input, two wind control ports todirect supply input flow to one or other of said outputs, wherein watercaught by the catcher is supplied to one control port to direct supplyinput flow to said first wind control output, the other control portbeing supplied from a feedback loop from said first wind control outputthat switches supply input flow to said second wind control output whenno water flows from said catcher.

Preferably, said first wind control output is connected to the radialport of a fountain supply vortex amplifier to provide a strong flowtherethrough, and said second wind control output is connected to atangential port of a vortex amplifier to provide a weak flowtherethrough, output from the fountain supply vortex amplifier supplyingthe fountain display.

Indeed, from a second aspect, the present invention provides a winddetection device comprising a catcher for liquid issuing from adetecting jet and falling under no-wind conditions, an outflow from thecatcher, and means to detect liquid in the catcher.

Said means to detect may comprise a pressure sensor sensitive tohydrostatic pressure of liquid in the catcher. Alternatively, said meansto detect may comprise a flow detector sensitive to outflow of liquidfrom the catcher.

Inherent in such a detection device is that, in high-wind conditionsless liquid falls into the catcher, so the outflow from it, or thehydrostatic pressure in it, is less than in no-wind conditions.Ultimately, in high-wind conditions, outflow from the catcher leads toboth the hydrostatic pressure and outflow reducing to zero. Whether thisoccurs very rapidly, so that the detector is sensitive to gusts, orslowly, so that the detector is sensitive only to sustained high-wind,is a matter of design choice. Indeed, there is no reason why thepressure or outflow detectors should not be sensitive enough to detectgradations of wind.

The wind detector is most suitable where there is already a source ofliquid under pressure, such as in fountain displays. In this event, andothers, the liquid is preferably water. The detecting jet is preferablyvertical, although it may be pointed in any direction provided thecatcher is positioned to receive the detecting jet in no-windconditions. The jet may be vertically down. The wind detector may beemployed with a fountain display according to the first aspect of thepresent invention, but equally it could be employed with moreconventional display fountains employing electrical/mechanical controls.Thus the flow/pressure detectors may be non-fluidic.

Preferably, manual control of a fountain display in accordance with thefirst aspect of the present invention is provided, comprising a manualdiverter having a manual input, first and second manual outputsdiverging from said manual input, first and second manual control portsto direct said input flow to one or other of said outputs, wherein eachcontrol port is supplied by a branch from said manual supply, eachbranch being controlled by a first restrictor and at least the firstcontrol port branch having a second restrictor, a selectively blockablevent being provided between said first and second restrictor whereby,when said vent is blocked, said restrictors are such that control flowis primarily through said first manual control port and, when said ventis not blocked, control flow is primarily through said second port.

Both branches may have a second restrictor, and both having aselectively blockable vent between said first and second restrictors ineach case.

A pilot diverter may be provided, comprising a pilot flow input, firstand second pilot outputs diverging from said pilot input, two pilotcontrol ports provided with control flow to direct pilot input flow toone or other of said pilot outputs, which pilot outputs comprise thecontrol ports of said primary diverter.

Multiple logic diverters may be connected in a logic circuit whereineach diverter has a logic flow input, first and second logic outputsdiverging from said logic input, two logic control ports provided withcontrol flow to direct logic input flow to one or other of said logicoutputs, which logic outputs comprise the control ports of any otherlogic diverter, any pilot diverter or said primary diverter.

Said pilot diverter may be in the form of a logic module receiving aplurality of inputs from different sources whereby the direction ofswitching of said primary diverter may be dependent on a plurality offactors controlled by said logic module.

A fountain display in accordance with the first aspect of the presentinvention may comprise a plurality of diverters, some providingalternating jets directly, and others feeding vortex amplifiersproviding alternating jets and sprays, each diverter being controlled bysaid logic module having a number of inputs, one of said inputs beingconnected to one output of a neighbouring diverter, and another of saidinputs being connected to the other output of said neighbouring diverteror to one output of a different neighbouring diverter.

A neighbouring diverter for a diverter on one side of the fountaindisplay may comprise a diverter on the opposite side of the display,whereby the display is topologically on the surface of a sphere.

Said diverters may be arranged in a square formation and each divertermay have eight neighbours, said logic module having four inputs on oneside and four on the other.

However, in a third aspect of the present invention, there is provided afountain display, comprising at least two display elements, each elementbeing driven by at least one output of a diverter directly associatedwith each element and controlled by a logic module, each divertercomprising an input for a supply of liquid, and first and second outputsdiverging from said input, and at least one control port selectivelyprovided with control flow to direct input flow to one or other of saidoutputs, and each logic module having at least two inputs and at leastone output connected to the control port of the diverter to provide saidcontrol port with said selective control flow, and wherein at least oneoutput of the diverter of one element is connected to one input of thelogic module of another element.

Preferably, each element has two modes of operation, one mode driven byone output of said associated diverter and the other mode being drivenby the other output of said associated diverter, said connection to saidinput of the logic module of said another element being a branch of oneof said outputs of said associated diverter.

Said logic module may comprise multiple logic diverters in a logiccircuit, wherein each logic diverter has a logic flow input, first andsecond logic outputs diverging from said logic input, two logic controlports provided with control flow to direct logic input flow to one orother of said logic outputs, which logic outputs supplies the controlports of any other logic diverter, or the, or one, output of the logicmodule.

The display elements may be in a formation in which each element issurrounded by N neighbouring ones of said elements and in which eachlogic module has N inputs, one from said branch of each neighbour. Theformation might be square, and N might be eight. Indeed, the number N ofneighbours and inputs may be the same for each element, the displaybeing arranged as a topological sphere.

In one embodiment, the display arranged to emulate a cellular automatondemonstrating the “Life” process of J H Conway. In another, it isarranged to emulate a cellular automaton demonstrating the “rule 30”algorithm of S Wolfram.

In a different aspect, the present invention also provides A fountaincomprising: a supply of water under pressure; a fluidic diverter havingan input for said supply, first and second outputs diverging from saidinput, and two control ports provided with control flow to direct inputflow to one or other of said outputs; a control loop interconnectingsaid control ports to cause oscillation of said direction of the inputflow; and a tapping in said control loop, whereby said control loop maybe supplied with water and/or drained of water to control the frequencyof said oscillation.

Preferably, said tapping is a first tapping connected to said supply, asecond bleed tapping being provided in the control loop between saidfirst tapping and one control port, whereby said first tapping admitsflow into the control loop, said second tapping drains flow from saidcontrol loop, whereby switching of the diverter may be controlled byrestricting said drainage. Restrictors may be provided around saidsecond tapping to adjust relative flow in the control loop on eitherside of the second tapping, and into the bleed.

The diverter may be arranged to be monostable to one of said outputports, temporary blocking or unblocking of said bleed tapping serving toswitch flow to the other of said output ports.

Embodiments of the invention are further described hereinafter, by wayof example, with reference to the accompanying drawings, in which:

FIGS. 1 a to f are schematic illustrations of diverters useful in thepractice of the present invention;

FIGS. 2 a to d are a schematic illustration of a diverter controlled bya pilot diverter, its symbolic representation, a circuit involving twosuch diverters, and a multi-stage register, respectively;

FIGS. 3 a to d are a side section, section on the line 1-1 in FIG. 3 a,section on the line 2-2 in FIG. 3 a, and a perspective view of a vortexvalve useful in the performance of the present invention;

FIGS. 4 a,b and c are side sections through nozzle arrangements usefulwith the vortex valve in FIG. 3;

FIGS. 5 a,b and c are side views of adaptations of the nozzles in FIG. 4and provided with swirl catchers.

FIGS. 6 a to g are side section and perspective views of differentnozzle arrangements;

FIGS. 7 a to d show variations of the vortex valve of FIG. 3, in sidesection, cross section, modified, partial cross section and modifiedcross section, respectively;

FIGS. 8 a,b and c show side section through a diverter of FIG. 1 (infact FIG. 1 a) combined with the vortex valve of FIG. 3 (a fountainelement in accordance with the present invention), in section in FIG. 8a, in perspective view in FIG. 8 b and symbolically in FIG. 8 c;

FIGS. 9 a to 9 c show various ways of employing the arrangements of FIG.8, but as a control valve rather than a direct fountain spray element;

FIGS. 9 d to 9 g show how various spray effects are achieved fromarrangements of diverters and vortex valves;

FIG. 10 is a section through a self oscillating nozzle, useful in someembodiments of the present invention;

FIG. 11 is a schematic illustration showing a wind detection andadjustment system, useful in a fountain system in accordance with thepresent invention;

FIG. 12 is a schematic circuit diagram showing a manual controlarrangement;

FIG. 13 is plan view of a fountain system in accordance with the presentinvention employing some of the arrangements illustrated in FIGS. 1 to12;

FIG. 14 a to c show further circuit control elements useful in fountainsystems according to the present invention;

FIG. 15 is a plan view schematically illustrating a fountain system inaccordance with a further embodiment of the present invention;

FIG. 16 is a detail of part of the system of FIG. 15;

FIG. 17 is a possible fluidic circuit arrangement to give effect to thelogic module shown in FIG. 16;

FIG. 18 is a diagram of a simpler logic circuit for a module receivinginputs from just two neighbours;

FIG. 19 is a diagram of a circuit for a fountain in accordance with thepresent invention;

FIG. 20 is a section through a swirl recovery unit;

FIG. 21 is a section through a swirl swamper;

FIG. 22 is a diagram of a circuit modified from FIG. 19 to providemanual control; and

FIG. 23 shows a universal base.

FIG. 1 a shows an unvented bistable fluid amplifier (fluidic diverter10), comprising a supply input 12, two control ports 14 a,b, and twooutputs 16 a,b. The supply flow is formed into a jet 17, which attachesto either the top or the bottom of a diverging section 18 of thediverter 10. Accordingly, the supply flow through the jet 17 will exitone or other of the outputs 16 a,b. All of the supply flow can beswitched to either output (100% diversion) if brief control flows areimposed on the control ports 14 a,b. If the outputs are unrestricted,flow can be entrained from the inactive output, so that the outflowappears to be greater than the supply flow (“more than 100% flowdiversion). The control flow needed to switch the diverter 10 depends onthe output restriction. Increasing restriction (thereby reducing thepercentage flow diversion) reduces the flow needed to switch thediverter (that is to say, the restriction increases the “gain”, butreduces the “stability”).

In FIG. 1 b, vents 20 a,b are shown in modified diverter 10 a. The vents20 a decouple the outputs 16 a,b, from one another so that there is noflow entrainment. Moreover, the amplifier 10 a acts as a logic element(flip-flop or memory device). It can be connected easily to othersimilar elements to transmit signals, because the vents 20 a,b isolateoperation of each device in the overall circuit.

FIG. 1 c shows the symbol employed herein in circuit arrangements. Thereference numerals are the same as those employed in FIG. 1 a. Indeed,the same reference numerals are applied throughout this specification torefer to essentially the same components, sometimes modified withsubscripts or superscripts to indicate modifications or differentexamples of the same unit.

FIG. 1 d shows a further diverter lob, having a cusped splitter 22between the two outputs 16 a,b. The twin cusps 22 promote are-circulation zone and provide a highly stable flow field. This isbecause, even should the active outlet 16 a or b be blocked, are-circulating flow can remain attached to the adjacent side wall of thediverging section 18. When the block is removed, flow continues down thesame branch.

GB-A-1297154 and 1363762 both disclose the use of a fluidic diverter toprovide oscillating flow. This is done by interconnecting the controlports of the diverter, as illustrated in FIG. 1 e, where the controlports 20 a,b are interconnected by a hose 24. The diverter must besuitably designed (ie not a high stability type) and the outputs must berestricted, as shown at 16 ′a,b). Sufficient restriction should be madeof the outputs 16 ′a,b to ensure 100% flow diversion. The frequency ofoscillation is determined by the inertia of the flow through the controlloop 24, and the pressure difference induced between the control portsby the main flow jet 17. Increasing flow increases the pressuredifferential and the result is that frequency is closely proportional tothe flow. Importantly, the time constant can be set by inertia andresistance (without the need for compliance—ie elasticity).Consequently, an incompressible fluid, such as water, can fill thecontrol loop 24 and produce a reliable dynamic response. In general, thelonger the control loop 24 is, the lower the frequency of oscillationwill be. On the other hand, the control loop 24 cannot be so long thatits resistance prevents the necessary flow to build-up and switch thediverter 10 c.

It is important to expel all air in the control loop 24, and one way ofdoing this is to provide a bleed tap (not shown) near the middle of thecontrol loop 24. This works provided that the pressure in the controlloop is greater than atmospheric. If the pressure is lower, then a smallwater feed into the control loop to purge the loop of air may berequired.

FIG. 1 f shows a diverter 10 d in which restricted outputs 16 ′a,b areprovided with branches 26 a,b that are fed back into the control ports14 a,b. The restrictions of the outputs ensure a strong feedback signal.These set the frequency by way of a predominantly inertial time constant(like the control loop 24 mentioned above). However, if compliance isintroduced into the feedback path, this influences the time constant.Indeed, increasing elasticity (or increasing inertance) decreases thefrequency. If elasticity is minimized, the inertial time constant isdominant and, like the control loop oscillator 10 c, the frequency isclosely proportional to the flow.

In FIG. 2 a, a two stage fluidic bistable amplifier 30 is shown. Here, afirst diverter 10 corresponds with any of the diverters discussed abovewith reference to FIGS. 1 a to f. However, its outputs 16 a,b form the20 control ports 14 ′a,b of a second diverter 10 e. This is shown insymbol form in FIG. 2 b. Such an arrangement can provide both pressureand flow gain. Typically, diverter 10 e is bigger than diverter 10,especially if the diverters are unvented devices.

Various logical functions can be produced by simple chains of bistableamplifiers. Four amplifiers can be used as two stages of a shiftregister. See, for example, FIG. 2 c. Here, two-stage amplifiers 30 a,bare connected in series, each serving as memory elements containing onebit of information each. Amplifiers 10 ₁ and 10 ₃ are memory elementscontaining one bit of information each, whereas amplifiers 10 ₂ and 10 ₄act as control gates. If the supply flow to the control gate is zero,there is no transmission of the state of amplifier 10 ₁ to amplifier 10_(3.) However, when a “shift signal” is fed to gates 10 ₂ or ₄ the stateof flow through the preceding amplifier 10 ₁ or ₃ is transmitted to thenext element in turn (ie diverter 10 ₃ or beyond diverter 10 ₄).

Thus, if the supply flow to diverter 10 ₁ is presently directed to theupper output (ie in the direction of the arrow A) then, when a shiftsignal is sent to supply 12 ₂ of diverter 10 ₂, its output will beswitched by the A output of diverter 10 ₁. It will be switched into anoutput in the direction of the arrow B from diverter 10 ₂. This willserve in turn to switch the supply entering diverter 10 ₃ from its input12 ₃ to the direction C, which it will then maintain even if the shiftsignal 12 ₂ into diverter 10 ₂ should subsequently cease. Likewise, thepreceding state of diverter 10 ₃ would be passed on to subsequentelements of the logic circuit by the diverter 10 ₄.

In a chain of more than two or three amplifiers, the flow gain may besubstantial. In that event, some of the amplifiers would typically bevented devices.

Such chains of amplifiers can be controlled in various ways. Forexample, the gating signals to the control amplifiers 10 ₂, 10 ₄ can beactivated in anti-phase (ie one on and the other off) thereby givingvery tight control of the progress of signals through the chain. Thesame surety can also be achieved by restricting the signal strengthtransmitted from the memory amplifiers 10 ₁, 10 ₃. Signals can onlytransmit when the gate amplifiers accept the weak signal, and then boostit to control the next amplifier. This onward transmission only occurswhen the gate amplifiers have a high supply flow, but they are thenimmune from the weak signals coming from the preceding memoryamplifiers. Hence a shift register can be made using two amplifiers perstage.

Various sequences of signals can be generated by feeding back signalsfrom the output to the input of a shift register. By feeding back simplelogic functions (for example exclusive-or) so called maximum lengthsequences can be generated (meaning the maximum possible length of bitsequence before repetition from the given number of memory elements inthe shift register). Hence, complicated sequences of events can becontrolled. FIG. 2 d shows a multi-stage fluidic shift register 30′.

Turning to FIGS. 3 a to d, a vortex valve 40 is shown having a supplyflow input 42 and a control flow input 43. The input 42 is received in ahousing 44, it being sealed thereto by an end cap 46. Inside the housing44, the supply input is perforated with regularly spaced holes 48(spaced both axially and circumferentially) so that the flow enters anannular duct 50 formed between the input pipe 42 and the housing 44. Theinput pipe 42 is sealed at its end by a centre body 52 that defines oneside of a vortex chamber 54. The other end of the vortex chamber isclosed by a nozzle plate 56 having a central nozzle 58.

The control flow input pipe 43 is connected to the nozzle plate 56 andis terminated by a tangential port 60 that connects the pipe 43 with thevortex chamber 54.

In the absence flow in the control pipe 43, flow in the pipe 42 exitsthrough the holes 48 and flows along the annular duct 50 and enters thevortex chamber 52 in a radial direction from around the entirecircumference of the centre body 52. Accordingly, there is nocircumferential component of the flow. It is entirely radial, as shownby the arrows in FIGS. 3 a and c. Accordingly, the output from nozzle 58may be a coherent, non-swirling jet that will exit the nozzle 58 as aclean column of liquid, with no spray or break-up.

However, if there is no supply flow 42, but only flow in the controlpipe 43, then the vortex chamber 54 is filled by supply through thetangential port 60. So that there is a swirling flow in the vortexchamber 54 as shown by the arrows in FIG. 3 b. In this event, the flowout of the nozzle 58 has substantial swirl and exits nozzle 58 as aconed spray. The cone angle is dependent on the geometry of the nozzleand the degree of swirl in the vortex chamber 54.

Accordingly, depending on whether flow to the vortex valve 40 is throughthe supply input 42 or the control input 43, the exit from the nozzle 58is either as a coherent jet or as a fine coned spray.

Referring to FIGS. 8 a to c, the vortex valve 40 is shown there used inconjunction with a diverter 10 to form a basic fountain 50 in accordancewith the present invention. In its simplest form, the fountain 50comprises a diverter 10 as described above with reference to FIG. 1 e.That is to say, one in which the control inputs 20 a,b areinterconnected by a control loop (not shown in FIG. 8 a). In this event,the flows to the respective outputs 16 ′a,b simply oscillate, so thatflows to the inputs 42,43 of the vortex valve 40 alternate with respectto one another. Thus, the output from the outlet nozzle 58 oscillatesbetween a straight jet and a coned spray.

In FIG. 8 b, it can be seen that diverter 10 has a rectilinearcross-section. This favours effective switching between the respectiveoutputs, both by virtue of the control inputs 20 being across the entiresection of the supply 12, as well as the jet flow having greater surfaceof the diverging walls 18 over which to attach thereto. However, in apractical embodiment, there is likely to be a smooth transition betweenthe round supply, control and delivery tubes connected to the diverter10, and the rectilinear sections of the diverter itself. The symbol forthe switched vortex valve 50 is shown in FIG. 8 c.

Returning to FIGS. 4 a to c, a nozzle plate 56 a is shown in FIG. 4 a. Anozzle body 57 can be screwed into a threaded aperture 55 of the nozzleplate 56 a. The nozzle body 47 has the nozzle aperture 58 and this canbe shaped to provide the desired jet. Where the two forms of jet are aswirling conical flow sheet, or a coherent jet, these are most readilyaccommodated by a smoothly chamfered inlet 59 of the nozzle 58 and asharp exit 61. In FIG. 4 b and c, a nozzle body 57′ is here held inplace by a threaded retaining ring 63 screwed onto a modified nozzleplate 56 b, which is provided with an O ring seal 67.

Turning to FIG. 5 a, one embodiment of retaining ring 63′ is shownhaving a pin 69 projecting therefrom and to which a swirl deflector disc71 is connectible. Disc 71 is provided with a central aperture 73through which jet flow from nozzle 58 can pass unimpeded.

However, when a diverging coned sheet flow (suggested by arrow 75 in thedrawings) emanates from the nozzle 58, it is deflected by the disc 71and evolves more as a horizontal spray, even more distinct from the jetthan the coned spray. Alternatively, an entirely spray destructiveshroud 71′ can be connected to the pin 69. The shroud 71 entirelycontains and destroys the conical spray 75 so that the output from thenozzle 58 appears only to comprise a pulsating jet. If that is verycoherent, its appearance is very appealing, emphasizing the motion ofthe water in an arcing flow.

FIG. 5 c shows how the disc catcher 71 may be implemented with a screwin nozzle 57′. Here, a disc 72 is formed integrally with the nozzle body57′ and to which the pin 69 is connected. To the pin 69, deflector disc71 or shroud 71′ can be connected as desired.

Referring to FIG. 6, various forms of nozzle plates 57′ are shown.

FIG. 6 a shows a basic nozzle 58 that gives a conical spray and a goodcoherent jet. In FIG. 6 b, nozzle 58 b has a chamfered exit so that aflat or very wide spray is delivered. However, it is more difficult forthe jet to remain coherent, so that any swirl is more likely with thisarrangement to lead to break-up of the jet. In FIG. 6 c, the nozzle 58 cis in the form of a flat slit across the face of the nozzle plate 57′.This results in a flat, triangular sheet-jet. In FIG. 6 d, a steppedbore nozzle 58d provides a very tight spray and a good jet. FIG. 6 eshows a multi-jet nozzle 58 e. FIGS. 6 f and g show a modified nozzleplate 57″ that is provided with a threaded bore 55′ to receive screw-innozzle bodies 58 similar to those described above with reference to FIG.4 a.

Turning to FIG. 7 a to d, a modified vortex valve 40′ is shown in whichthe control pipe 43′ now surrounds the housing 44 and has a number oftangential control ports 60′. However, to direct the flow tangentially,the wall of the housing 44 has to have a substantial thickness, so thata tangential flow direction can be provided by the ports 60′.Alternatively, vanes 75 may be disposed across the wall 44, so that flowfrom the annular control duct 43′ into the vortex chamber 54 is causedto swirl by those vanes 75 on passing through the openings 60′. Also, asshown in FIG. 7 c, straightening vanes 77 can be provided on the centrebody 52 so that flow through the supply pipe 42 can be maintainedabsolutely axial.

Referring to FIGS. 9 a to g, various combinations of the foregoingcomponents are illustrated. In FIG. 9 a, the switched vortex valve 50′is shown delivering an output outflow on line 76 that is led to anotherdevice or system. The effect of the diverter 10/vortex valve 40′combination is that the supply flow 12 is modulated at the output 76 bythe control flows 20. When the vortex valve 40′ is supplied by output 16b of the diverter 10, then no vortex swirl is produced in the vortexchamber 54 of the vortex valve 40′. Therefore, a high flow rate is seenat the output 76. On the other hand, if the output of the diverter 10 isthrough line 16 a, then this enters the vortex valve 40′ tangentially.This causes a vortex in the chamber 54 and so increases the resistanceof the valve to flow. A relatively small output flow is then seen at theoutlet 76.

In FIG. 9 b, a diverter 10 is shown with its outputs 16 a,b connected totwo vortex valves 40 a,b. Each vortex valve has its own radial supply 42a,b so that, depending on the switched state of diverter 10, vortexvalves 40 a,b will alternate between respective jet flow and spray flow.In FIG. 9 c, the arrangement is as in FIG. 9 b except that the vortexvalve 40 ′a,b are as shown in FIG. 9 a, and are used to provide flow foranother device or system from their outputs 76 a,b.

In FIG. 9 d, two diverters 10 a,b are used to control a single vortexvalve 40″ having opposed control flow inputs 43 a,b. This provides forpotential modes of operation depending on the four possible combinationsof the outputs from diverters 10 a,b. Indeed, the four output states ofthe flow from nozzle 58 are described in the Table I above for amplifierB.

In FIG. 9 e, a variation is shown in which the control nozzles 43 a, 43′b of vortex valve 40″′ are in the same direction. Table I abovedescribes the outflow through the nozzle 58 of the vortex valve 40″′(amplifier A), depending on the states of outputs of the diverters 10a,b.

FIG. 9 f shows the symbolic representation of the arrangement describedwith reference to FIG. 1 e above in which a control loop 24 is employedto provide oscillatory flow at the control inputs 20 a,b of diverter 10.Indeed, the arrangement shown in FIG. 9 g is perhaps the simplestembodiment of fountain in accordance with the present invention, inwhich the input supply 12 is connected to a source of water underpressure (eg mains supply) and the output from the nozzle 58 is either aspray or a single jet. Such an arrangement is simple and inexpensive tomanufacture and yet provides an alternating display not presentlyavailable so simply.

FIG. 9 g shows an arrangement as described above with reference to FIG.9 e, but where control loops 24 a,b for the two diverters 10 a,b areprovided, each of different length. Each diverter switches with adifferent frequency, therefore, and this results in a somewhat random,or cyclic, appearance to the four output states from the nozzle 58 ofthe vortex valve 40″′.

FIG. 10 illustrates a self-oscillating vortex nozzle 80 comprising flattop and bottom walls 82, a circular vortex chamber 84 and an inputchamber 86. The input chamber 86 has a supply port 88 in the wall 82 andthe vortex chamber 84 has a central outlet nozzle 90 disposed in thewall 82 that is opposite the wall containing supply port 88. A waist 92defines the interface between the inlet chamber 86 and the vortexchamber 82. It is found that, in operation, flow into the inlet chamber86 transitions into the vortex chamber 84 and oscillates between directflow (that issues from the nozzle 90 as a jet), and swirling flow(resulting in a spray issuing from the nozzle 90). The swirling flow isfirst clockwise, then anti-clock wise and switches back and forth.

Referring now to FIG. 11, a wind detection system 100 comprises avertical nozzle and water jet 102 and a surrounding catcher basin 104.The diameter of the basin 104 is designed to be so small that only windof less velocity than a certain, predetermined velocity will permit thewater issuing from the nozzle 102 to be caught by the basin. Wind of anygreater velocity will deflect the jet so that it falls beyond the edgeof the basin 104. The catcher 104 feeds a vertical columnar collector106. The wind state is detected by a fluid amplifier 10 ₁ having a smallsupply flow 12 ₁. Control input 20 a of the amplifier 10 ₁ is providedby the collector 106. At low wind speed, the control signal here isstrong, and the amplifier is switched to output 16 b. Control input 20 bis supplied by a feedback bias from output 16 b, but the feedback flowis insufficient to overcome the control flow from the wind detectorduring low wind conditions. However, should a high wind develop so thatthe catcher 104 empties and no flow comes from the collector 106, thefeedback bias from output 16 b is sufficient to switch diverter 10 ₁.Its output then appears on output 16 a. The outputs from diverter 10 ₁are further amplified by a second bistable amplifier 10 ₂. More stagescould be added to provide control signals to the water supply system,for example, to the fountain system.

With reference to FIG. 12, a manual control system is provided by adiverter amplifier 10 provided with a supply 12 that has two branches 13a,b that supply control inputs 20 a,b of the diverter 10. Both branches13 a,b are controlled by restrictors R₁, R₂. However branch 13 a isprovided with a further restrictor R₃, and, between restrictors R₁ andR₃, a selectively blockable vent V is provided. Under normal, unblockedconditions, restrictor R₃ and vent V conspire to ensure thatsubstantially no flow is provided at control 20 a. In that event,diverter 10 is switched by the flow through restrictor R₂ and controlport 20 b so that its supply 12 exits on output 16 a. However,restrictors R₁ to R₃ are arranged so that, should vent V be selectivelyblocked, a more powerful flow is provided by control port 20 a, so thatdiverter 10 is switched to output 16 b. Indeed, in this respect, branch13 b provides a reset signal in the absence of activation of branch 13 aby blocking vent V. However, an alternative arrangement would be toduplicate branch 13 a in branch 13 b, whereupon a bistable arrangementwould be provided capable of being switched by blocking either of thevents.

FIG. 13 discloses a fountain system 110 embodying the present inventionand employing some of the components described above. Here, a main pump112 supplies water under high pressure. The output 114 immediatelybranches into a high pressure branch 116 and a branch leading to a jetpump 118 that entrains flow from a source 120 to provide a high flowbranch 122. The high flow branch supplies two vortex valves 40 a,b in anarrangement as described above with reference to FIG. 9 b. The vortexvalves are controlled by a diverter 10 which is operated in amono-stable mode under the control of a wind detector 100, andsubstantially as described above with reference to FIG. 11. The onlymodification is that the bias is provided by a branch of the highpressure supply 116. A signal amplifier 124 outputs the signal from thewind detector 100 to the diverter 10.

The arrangement is such that, in low wind conditions, vortex valve 40 bis set to high resistance so that the high flow supply in line 122 isimpeded and results in a low flow supply in output 126. However, radialflow is permitted through vortex amplifier 40 a, so its output 128 is inhigh flow during low wind conditions.

Output 126 supplies a ring 125 of three fountain devices 50 a,b,c and acentral fountain 50 d, all of which are substantially as described abovewith reference to FIG. 8. Whereas fountain 50d may be under automaticcontrol by a closed loop, for example (as described above with referenceto FIG. 9 f) high pressure line 116 may also supply a manual controldevice 130 (operating substantially as described above with reference toFIG. 12). This is arranged to control the ring of fountains 50 a,b,c.

On the other hand, output 128 from the vortex valve 40 a supplies twoouter rings 127 of devices, an inner ring 129 of oscillating valves 80(substantially as described above with reference to FIG. 10) and anouter ring 131 of diverter fountains 10′. Here, the diverter outputs 10′are themselves provided with nozzles to deliver alternating jets ofwater. Again, the high pressure supply 116 is fed to a signal generator30″, which controls the sequencing of the diverter jets 10′. The signalgenerator 30″ may be a sequence generator controlling all the diverters10′ so that they switch in sequence to produce a “Mexican wave′.Alternatively they may be switched in phase.

Turning to FIG. 14, the diverters 10′ of the ring 131 in the fountainsystem 110 of FIG. 13, may include an integrated, small pilot amplifier10″. This would enable small signal flows sent from the central controlunit 30″ to switch the diverters 10′.

Using the concept of piloted fluidic display devices, the controlsequences could conceivably be implemented by the display devicesthemselves, if suitable interconnections were made. For example, with anarray of N diverters and switched vortex valves, correct interconnectionfeedback would enable the array to go through a sequence of 2^(N)different combinations of right/left events (diverter fountains 10′), orspray/jet events (diverter vortex amplifier combinations 50) beforerepetition. In effect, the individual display devices (albeit supportedby their pilot stage) would constitute elements of the shift registersequence such as described above with reference to FIGS. 2 c and 2 d.

A further advance is shown in FIG. 14 b and c, which would be to attacha logic module 132 to a diverter 10. In FIG. 14 b, the diverter 10comprises the fountain element itself. On the other hand, in FIG. 14 c,the diverter is part of a switched vortex valve 50. In either event, thelogic module has its own supply 134 that appears at one of its outputs136 forming the control inputs of the diverter 10. Multiple inputs fromother sources can be integrated to provide an output on either line 136depending on which inputs are active.

With an arrangement such as this, an array 150 of fountain devices canbe internally controlled. In FIG. 15, a central array of switched vortexvalves 50 are shown with a surrounding array of diverters 10. Eachdevice is connected by input and output signals to the surrounding eightdevices. At the edges of the display 150, signals from one side aretransmitted to the opposite edge, so that a topological sphere isprovided.

Turning to FIG. 16, a single fountain element 10/50 is illustratedhaving eight surrounding elements 1 to 8. Each of the surroundingelements has a diverter output A or B. The A branches of surroundingfountain elements 1, 6, 7 and 8 are connected to inputs 1, 6, 7 and 8respectively of logic controller 132 of the device 10/50. The remainingsurrounding devices 2, 3, 4 and 5 have their B outputs connected toinputs 2 to 5 of logic controller 132. How logic controller 132 isconfigured is a matter for discretion and design choice, but onepossible switching regime is illustrated in Table II below. TABLE IINumber of Active Consequent Next Inputs Current State Output State 1, 2,4, 5, 6, 7 or 8 Left Stay Left 1, 4, 5, 6, 7 or 8 Right Switched Left 3Left Switched Right 2 or 3 Right Stay Right

In any event, depending on the logic mode chosen, the output of device10/50 is to one of its two outputs 136, that is to say, A or B. It is tobe noted that the outputs A,B of the device 10/50 each have fourbranches leading to one each of four of the eight surrounding devices 1to 8, providing inputs to their logic modules 132 ₁ to 132 ₈.

When connected in this way, the array emulates a classic cellularautomaton (“Life”, created by John Horton Conway). As a result, thefountain display 150 could replay any of the well established complex(and sometimes perpetual) sequences. Further possibilities in cellularautomata are provided by Stephen Wolfram (“A New Kind of Science” ISBN1-57955-008-8, Wolfram Media Inc, 2002) who has recently explored andcompletely characterised many hundreds of millions of binary algorithms.In principle these could be implemented by advanced fluid fountains.

Conceivably, very large arrays of devices could be assembled which wouldundergo the highly complex “Life” and “Death” phases of cellularautomata. The onlooker would see waves, whirls, spasms and inactivities,typical of systems which currently only exist on computer driven videodisplay units.

FIG. 17 shows schematically a possible arrangement of a logic controlmodule 170 of the type schematically illustrated as module 10/50 in FIG.16. This arrangement reproduces the “Life” automaton referred to above.It has eight control inputs C₁-C₈, each supplied by a neighbour's activeoutput. The inputs are combined in a network of Y-joints 172, whichproduces a summation of the signals. This summed signal is applied tothree monostable threshold gates, TGa, TGb and TGc, through weightingrestrictors R₁ which set the signal strength that causes each gate toswitch. Gate TGa is caused to switch inactive if 2 or more inputs C₁₋₈are active, gate TGb is switched inactive if 3 or more inputs areactive, and gate TGc is switched by 4 or more of inputs C₁₋₈ beingactive. Logical processing of the resulting logical functions is thendone by fluidic logic devices: two NOR-gates B and S, and two bistable(memory) devices C and N. Bistable N has two control inputs on one sideequivalent to an OR function of those inputs. Bistable C holds thecurrent state Alive or Dead of the “cell” represented by the wholecircuit. Signals from bistable C are combined with the logical functionsfrom the threshold gates in the NOR gates B & S. NOR gate B generates asignal implying “birth” of a cell from an originally dead state. NORgate S generates a “sustain” signal which maintains the existing livestate of a cell. These signals, which both generate a live state for thenext time phase of the automaton, are fed to the next-state bistable N.Bistable N holds the logical state ready for transfer to the“current-state” bistable C via feedback lines F connecting to the inputcontrol ports of bistable C. “Death” is produced by a bias signal BS fedfrom the common fluid power supply S via a restrictor R₂; this resetsbistable N to the “die” command, unless countermanded by the controlinputs from NOR gates B or S.

The cell and the overall cellular automaton exists in a sequence ofdiscrete states controlled by a centrally generated clock signal TS. Atregular intervals this activates bistable N and sends strong signals tochange the state of bistable C. By attenuating the signals from N byrestrictors (not shown) in the feedback lines, only a very largetransfer signal is able to effect the signal transmission. At this highsupply power the bistable N is immune from the relatively weak logicsignal S from the NOR gates. Hence race hazards are avoided (signalsracing round the signal feedback loop out of synchronism with the clocksignal).

The fountain display element is bistable C or some other devicecontrolled by it. The cell communicates to others in the array by LIVE(active) signals sent from the appropriate output of bistable C.

FIG. 18 shows schematically a possible arrangement of a fluidic logiccontrol module 180. This represents one “cell” of a different cellularautomaton to that described above. Here, the logical algorithm and thecorresponding circuit implement the “rule 30” automaton discovered anddescribed by Stephen Wolfram, (reference above). The cell exists in asequence of discrete states, each determined by the state of the celland its two neighbours. The current state of the cell, ALIVE or DEAD isheld in bistable memory element CC. A signal from this, and inputsignals L and R from left and right neighbouring cells, are processed bya logic circuit consisting of an active OR-gate AO and an exclusiveOR-gate EO. The active OR-gate AO is a fluidic monostable switchingdevice and therefore does not attenuate the signal. The exclusiveOR-gate EO is not active and therefore also does attenuate the signals.

The output of the exclusive-OR gate EO is the signal fed to bistablememory element NN holding the next state for the cell. The signal fromthe exclusive OR-gate signifies “ALIVE” for the next state. A biassignal returns the bistable NN to its “DEAD” state in the absence of anoutput from the exclusive-OR gate. The time-sequence of states for thecell, and the whole automaton, is controlled by a centrally generatedclock signal TS. At regular intervals, this activates bistable NN andsends strong signals to change the state of bistable CC. By attenuatingthe signals from NN by restrictors (not shown) in the feedback lines FF,only a high pressure transfer signal is able to effect the signaltransmission. At this high supply power, the bistable NN is immune fromthe relatively weak logic signals from the exclusive-OR gate and thebias signal. Only when TS is very low or near zero can its state becontrolled by the bias or exclusive OR-gate. However at this low supplypressure bistable NN cannot affect bistable CC. This ensures that the“current” and “next” states are separated by finite time periods andthat signals do not race around the system out of synchronism with thetransfer signals.

Signals to the cell's neighbours are provided by bistable CC. As part ofa fountain, bistable C might be a jet diverter, so acting as a displayelement itself, or it might control other diverters and/or vortexvalves.

Wolfram's “rule 30” automaton is defined in terms of a one-dimensional(a line) array and the foregoing description conforms to thatdefinition. Wrapping up linearly connected cells to form a square orother two-dimensional figure can produce two-dimensional arrays. Othertwo-dimensional arrays can be produced by slight modifications to theinterconnections within and between cells. As an example, the next-statebistables could feed signals to cells in a neighbouring row, rather thanthe internal feedback to bistable CC just described.

The logical function generated by the circuit isNext-State=L v(R v Current-State)

where v signifies the OR-function and v signifies exclusive-OR

The resulting function is shown in Table III below in which 1 signifies“alive” and 0 “dead. TABLE III L Current State R Next State 0 0 0 0 0 01 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0

Turning to FIG. 19, a diverter 10 f is shown in a circuit 30 f inaccordance with an embodiment of the present invention. Here, a diverterwith fixed construction, particularly a diverter with a fixed length anddiameter of control loop 24 f, the frequency of oscillation is afunction mainly of supply flow 12 f. part from changing the supply flow,the frequency is difficult to adjust. However, if a small amount of flowis added to or extracted from the control loop, the frequency can bealtered. A reason for doing this is to optimise the visual effect of thedisplay. Flow can be added by tapping-off some of the supply flow, whichis always at a higher pressure than in the control pipe via valve 1.Flow can be passively bled to atmosphere or pond through valve 2 if thecontrol loop pressure is above that of the atmosphere or the pond.

Adding flow decreases the frequency, and extracting flow increases thefrequency. It is not always possible to simply bleed flow from thecontrol loop, however, because for a simple diverter not connected to avortex valve, the control loop pressure is often too low or may even besub-atmospheric. A passive bleed valve 2 would then merely admit air,which would be detrimental.

When the diverter is connected to a vortex valve, the control looppressure is usually higher than atmospheric, so bleeding flow ispractical. For the cases where the control loop is at low pressure, awater driven jet pump or ejector (not shown) could be used to suck flowfrom the control loop 24 f (via valve 2).

The ability to inject or extract control loop flow has the added benefitthat it can assist in purging the control loop 24 f of air wheninitially switched on. Also it serves to wash debris from the controlloop.

In order for the control loop oscillator to oscillate regularly, theoutput resistance on the diverter (ie on both outlets 16 a,b equally ina symmetrical diverter) must be correctly adjusted. If the resistance istoo small (i.e no blockage, or a virtually free exit path), the divertermay cease to oscillate because sensitivity or “gain” of the fluidicamplifier (fluidic diverter) drops at high outflows. As the outletresistance is increased, gain increases and oscillation is easier toensure. However, if the outlet resistance is too high, the flow cannotbe diverted (in the limit at very high resistance, it splits equallybetween the two outlets 16 a,b), so a compromise must be found.

For the diverter 10 f acting as a fountain, the two outlets are, infact, the fountain jets. They are easily accessible and can be adjustedor exchanged to obtain the best effect. For the diverter-switched vortexvalve, the outlet resistance is built-in to the overall system. Thetangential nozzle (60, FIG. 3 a, for example) in the vortex valve 40forms one diverter outlet resistance (which can be well defined at thedesign stage), but the other outlet 50 is simply the non-swirling supplyduct, typically along the axis of the vortex valve. If this resistanceis too small, poor oscillation may occur. Hence it is important toensure that, if no adjustment can be made, adequate restriction is builtin. Alternatively, “fine tuning” may be provided during finalcommissioning of a device. Such tuning could be made by various knownarrangements such as needle-, gate-, butterfly- or ball-type valves.

Two additional methods of modifying the outflow apply to the switchedvortex device, as shown in FIGS. 20 and 21. In the first method, theswirling flow (in the vortex mode of operation) is captured in anannular plenum 175 of vortex valve 56 f. An annular diffuser 177 leadsfrom the exit nozzle 58 f, which is either flat or conical, as shown.Dynamic pressure in the swirl flow is converted to static pressure inthe plenum 175. Nozzle(s) 179 fed from the plenum produce a jet or jetsduring the vortex phase of operation. The jets 179 can be arrangedaround the central axis of the vortex valve pointing upwards andoutwards to give an intermittent “crown-like” or “flower-like” spray ofwater on every switching cycle of the device. Alternatively apressurised water signal can be drawn from the plenum via a pipe to actas a switching signal for other devices. To recover pressuresuccessfully, the annulus 177 must be narrow and its entry point closethe vortex nozzle exit 58 f, as shown.

The second method involves surrounding the exit nozzle 58 g (see FIG.21) from the vortex valve with a cup-like container 181. Water can bemade to submerge the nozzle, thereby modifying the appearance of theoutflow. A deeply submerged nozzle produces an attenuated outflow,particularly in the vortex state. The spray can be completely suppressedif desired.

If the cup has a small volume, the contents can quickly get swept awayby the outflow, so unless the water is replenished, the effect istransient. If the cup has a large area and volume, the water may beself-replenishing and the effect permanent. If water flow to and/or fromthe cup is controlled by some independent means then this enables theappearance of the fountain to be controlled, perhaps by onlookers or byautomatic, even fluidic, methods. For example the cup 181 may beprovided with an overflow 183, whose exit may be controlled. When full,the cup may only permit the central jet to exit, but when allowed toempty, both the central jet and vortex, modified as the cup fills, maybe seen.

A fluidic diverter tends to suck flow into its control ports, even whenthe outputs are loaded by significant restrictions. It is easytherefore, in principle, to switch manually a diverter (ie one without aclosed control loop) simply by blocking one of the control ports. Thismethod has disadvantages however. In a water flow system, the inflow tothe control should be water, so the control port to be blocked should besubmerged. If air enters, operation is very erratic. Submergence mightbe inconvenient for many applications. Furthermore, even if submerged,the sucked-in control flow might be a source of contamination byunfiltered pond water, for example.

A better method of manual control is shown in FIG. 22. This uses asystem of restricted feeds and bleeds to enable the blockage of asensing port to switch the diverter.

In the absence of manual input, small flows feed from tappings 185 ofthe supply 12 g via restrictors 1 a an 1 b to the control ports 14 a,b.Flow is restricted by restrictors 2 a and 2 b, a slight excess beingbled through restrictors 3 a and 3 b to atmosphere along lines 187 a,b.These bleed flows ensure that air, or external pond water, does notenter the system. The restrictors are set to enable the diverter to bestable when there is no manual input.

Blocking one of the bleeds 187 a,b manually causes all the flow from theassociated flow feed to enter the control port and when properlyadjusted, to switch the diverter. The output of such a manuallycontrolled diverter can, in principle, be communicated to any otherfluidic device in an array. Indeed, the arrangement could be arranged tobe monostable, with only one bleed (eg 187 a) being manually operated,the other being permanently sufficient to maintain the flow to output 16a while bleed 187 a is unblocked.

A “universal base” system is shown in FIG. 23. Here, a diverter isemebedded in a rather sturdy, and perhaps massive, base block 190 ofcement or similar rigid material. Both upward 192, and horizontal 194,outlets are incorporated. Normally, unused outlets would be blocked by astopper (not shown). The upward outlets 192 can have pipe-mountednozzles 196 attached, or can feed a vortex valve 198 to produce thealternating spray-jet display. In both cases, the base is sufficientsupport. Outlying nozzle(s) 200 can be supplied for connection to thehorizontal outlets 194.

A purge valve 202 is fed from close to the supply inlet. A tee (notshown) in the control loop can be embedded in the base block. Thus thewhole system constitutes a kit of parts which enables several displayoptions to be chosen.

1. A fountain comprising: a supply of water under pressure; a primaryfluidic diverter having an input for said supply, and first and secondoutputs diverging from said input, two control ports provided withcontrol flow to direct input flow to one or other of said outputs; and avortex amplifier comprising a vortex chamber, a radial port, a vortexinducing port and an axial output port; wherein one of said first andsecond primary diverter outputs is connected to said vortex inducingport and the other is connected to said radial port, said axial portleading to a nozzle whereby an alternating vortex spray or axial jet isproduced.
 2. A fountain as claimed in claim 1, in which said controlports are interconnected by an inertia loop, whereby oscillations areinduced in the control flow to switch flow alternately between saidfirst and second outputs.
 3. A fountain as claimed in claim 1, in whichsaid first and second outputs of said diverter are vented to isolateeach output from the input.
 4. A fountain as claimed in claim 1, inwhich said outputs have restrictors therein and include feed back loopsinto said control ports, whereby oscillations are induced in the controlflow to switch flow alternately between said first and second outputs.5. A fountain as claimed in claim 1, in which said diverter is cuspedbetween said first and second outputs to increase stability of flowthrough said first and second outputs.
 6. A fountain as claimed in claim1, in which said vortex amplifier comprises an annular chamber formed bya tubular housing and central body, supply flow to the amplifierentering said annular chamber at one end, the other end of the annularchamber being terminated by a nozzle plate defining with said centralbody said vortex chamber, said housing having an opening forming saidvortex inducing port.
 7. A fountain as claimed in claim 6, in which saidvortex inducing port is a passage from a supply chamber outside saidhousing and arranged tangentially with respect to said vortex chamber.8. A fountain as claimed in claim 6, in which said vortex inducing portcomprises a plurality of said openings in said housing, each openingprovided with a vane to tangentially direct radial inflow from a supplychamber surrounding said housing.
 9. A fountain as claimed in claim 1,in which said nozzle is interchangeable with different nozzlesdisplaying one of various spray patterns when vortex spray issuestherefrom.
 10. A fountain as claimed in claim 1, in which a spraycatcher is disposed beyond the nozzle to deflect vortex spray issuingfrom said nozzle, the catcher having an orifice to permit passage ofsaid axial jet to flow unimpeded.
 11. A fountain as claimed in claim 10,in which the catcher is inverted so as to destroy entirely said vortexspray.
 12. A fountain system incorporating a fountain as claimed inclaim 1, in which two of said vortex amplifiers are provided inparallel, each with its own supply to its radial port, each vortexinducing port being connected to one or other of said first and secondoutputs of the primary diverter.
 13. A fountain system as claimed inclaim 12, in which said axial outputs of the two vortex amplifiers leadto further components of the system which are arranged to be controlledby greater or lesser flow rates that issue from said axial outputs ofthe vortex amplifiers depending on whether there is flow into saidvortex inducing port.
 14. A fountain system incorporating a fountain asclaimed in claim 1, in which two of said primary diverters are providedwhose first outputs are joined together and comprise the radial inputfor said vortex amplifier, and whose second outputs are connected toseparate vortex inducing ports of said vortex amplifier, whereby severalmodes of operation of the vortex amplifier results.
 15. A fountainsystem as claimed in claim 14, in which said control ports of eachprimary diverter are interconnected by an inertia loop, wherebyoscillations are induced in the control flow to switch flow alternatelybetween said first and second outputs, and in which said control loopsare of different length.
 16. A fountain system incorporating a fountainas claimed in claim 1, in which a self-oscillating vortex nozzle isprovided, comprising a cylindrical vortex chamber having a centraloutput nozzle and an input comprising a section of the cylindrical wallof the chamber to which an input chamber is connected, a narrowing ofthe input chamber being provided at the input section of the vortexchamber, whereby flow entering the vortex chamber oscillates betweenswirling entry and straight radial entry leading to oscillations in theoutput between a straight jet and a swirling spray.
 17. A fountainsystem incorporating a fountain as claimed in claim 1, in which a winddetection and adjustment device is provided, comprising a catcher forwater issuing from a fountain display and falling under no-windconditions, and a wind control diverter having a supply input, first andsecond wind control outputs diverging from said supply input, two windcontrol ports to direct supply input flow to one or other of saidoutputs, wherein water caught by the catcher is supplied to one controlport to direct supply input flow to said first wind control output, theother control port being supplied from a feedback loop from said firstwind control output that switches supply input flow to said second windcontrol output when no water flows from said catcher.
 18. A fountainsystem as claimed in claim 17, in which said first wind control outputis connected to the radial port of a fountain supply vortex amplifier toprovide a strong flow therethrough, and said second wind control outputis connected to a tangential port of a vortex amplifier to provide aweak flow therethrough, output from the fountain supply vortex amplifiersupplying the fountain display.
 19. A fountain system incorporating afountain as claimed in claim 1, in which manual control is provided,comprising a manual diverter having a manual input, first and secondmanual outputs diverging from said manual input, first and second manualcontrol ports to direct said input flow to one or other of said outputs,wherein each control port is supplied by a branch from said manualsupply, each branch being controlled by a first restrictor and at leastthe first control port branch having a second restrictor, a selectivelyblockable vent being provided between said first and second restrictorwhereby, when said vent is blocked, said restrictors are such thatcontrol flow is primarily through said first manual control port and,when said vent is not blocked, control flow is primarily through saidsecond port.
 20. A fountain system as claimed in claim 19, in which bothbranches have a second restrictor, and both have a selectively blockablevent between their respective first and second restrictors.
 21. Afountain system incorporating fountain as claimed in claim 1, in which apilot diverter is provided, comprising a pilot flow input, first andsecond pilot outputs diverging from said pilot input, two pilot controlports provided with control flow to direct pilot input flow to one orother of said pilot outputs, which pilot outputs comprise the controlports of said primary diverter.
 22. A fountain system as claimed inclaim 21, in which said pilot diverter is in the form of a logic modulereceiving a plurality of inputs from different sources whereby thedirection of switching of said primary diverter may be dependent on aplurality of factors controlled by said logic module.
 23. A fountainsystem incorporating a fountain as claimed in claim 1, in which multiplelogic diverters are provided connected in a logic circuit, wherein eachlogic diverter has a logic flow input, first and second logic outputsdiverging from said logic input, two logic control ports provided withcontrol flow to direct logic input flow to one or other of said logicoutputs, which logic outputs supplies the control ports of any otherlogic diverter, any pilot diverter or said primary diverter.
 24. Afountain system as claimed in claim 23, comprising a plurality ofdiverters, some providing alternating jets directly, and others feedingvortex amplifiers providing alternating jets and sprays, each diverterbeing controlled by said logic module having a number of inputs, one ofsaid inputs being connected to one output of a neighbouring diverter,and another of said inputs being connected to the other output of saidneighbouring diverter or to one output of a different neighbouringdiverter.
 25. A fountain system as claimed in claim 24, in which aneighbouring diverter for a diverter on one side of the fountain displaycomprises a diverter on the opposite side of the display, whereby thedisplay is topologically on the surface of a sphere.
 26. A fountainsystem as claimed in claim 25, in which said diverters are arranged in asquare formation and each diverter has eight neighbours, said logicmodule having four inputs on one side and four on the other. 27.(canceled)
 28. A wind detection device comprising a catcher for liquidissuing from a detecting jet and falling under no-wind conditions, anoutflow from the catcher for liquid caught by the catcher, and means todetect liquid in the catcher.
 29. A wind detection device as claimed inclaim 28, in which said means to detect comprises a pressure sensorsensitive to hydrostatic pressure of liquid in the catcher.
 30. A winddetection device as claimed in claim 28, in which said means to detectcomprises a flow detector sensitive to outflow of liquid from thecatcher.
 31. A wind detection device as claimed in claim 28, in whichthe detecting jet is vertical.
 32. A wind detection device as claimed inclaim 31, in which the jet is vertically upwards, from the centre of thecatcher.
 33. A wind detection device as claimed in claim 28, in whichsaid means to detect is non-fluidic.
 34. (canceled)
 35. A fountaindisplay, comprising at least two display elements, each element beingdriven by at least one output of a diverter directly associated witheach element and controlled by a logic module, each diverter comprisingan input for a supply of liquid, and first and second outputs divergingfrom said input, and at least one control port selectively provided withcontrol flow to direct input flow to one or other of said outputs, andeach logic module having at least two inputs and at least one outputconnected to the control port of the diverter to provide said controlport with said selective control flow, and wherein at least one outputof the diverter of one element is connected to one input of the logicmodule of another element.
 36. A fountain display as claimed in claim35, wherein each element has two modes of operation, one mode driven byone output of said associated diverter and the other mode being drivenby the other output of said associated diverter, said connection to saidinput of the logic module of said another element being a branch of oneof said outputs of said associated diverter.
 37. A fountain display asclaimed in claim 36, in which said logic module comprises multiple logicdiverters in a logic circuit, wherein each logic diverter has a logicflow input, first and second logic outputs diverging from said logicinput, two logic control ports provided with control flow to directlogic input flow to one or other of said logic outputs, which logicoutputs supply the control ports of any other logic diverter, or the, orone, output of the logic module.
 38. A fountain display as claimed inclaim 36, in which the display elements are in a formation in which eachelement is surrounded by N neighbouring ones of said elements and inwhich each logic module has N inputs, one from said branch of eachneighbour.
 39. A fountain display as claimed in claim 38, in which thenumber N of neighbours and inputs is the same for each element, thedisplay being arranged as a topological sphere.
 40. A fountain displayas claimed in claim 38, in which the formation is square, and N iseight.
 41. A fountain display as claimed in claim 38, arranged toemulate a cellular automaton demonstrating the “Life” process of J HConway.
 42. A fountain display as claimed in claim 38, arranged toemulate a cellular automaton demonstrating the “rule 30” algorithm of SWolfram.
 43. A fountain display as claimed in claim 35 incorporating awind detection device comprising: a catcher for liquid issuing from adetecting jet and falling under no-wind conditions; an outflow from thecatcher for liquid caught by the catcher; and means to detect liquid inthe catcher.
 44. A fountain comprising: a supply of water underpressure; a fluidic diverter having an input for said supply, first andsecond outputs diverging from said input, and two control ports providedwith control flow to direct input flow to one or other of said outputs;a control loop interconnecting said control ports to cause oscillationof said direction of the input flow; and a tapping in said control loop,whereby said control loop may be supplied with water or drained of waterto control the frequency of said oscillation.
 45. A fountain as claimedin claim 44, in which said tapping is a first tapping connected to saidsupply, a second bleed tapping being provided in the control loopbetween said first tapping and one control port, whereby said firsttapping admits flow into the control loop, said second tapping drainsflow from said control loop, whereby switching of the diverter may becontrolled by restricting said drainage.
 46. A fountain as claimed inclaim 45, in which restrictors are provided around said second tappingto adjust relative flow in the control loop on either side of the secondtapping, and into the bleed.
 47. A fountain as claimed in claim 45, inwhich said diverter is arranged to be monostable to one of said outputports, temporary blocking or unblocking of said bleed tapping serving toswitch flow to the other of said output ports.
 48. A fountain as claimedin claim 45, in which a third bleed tapping is provided in the controlloop on the other side of said first tapping remote from said secondbleed tapping.
 49. A fountain as claimed in claim 1, in which saidnozzle opens into an annular diffuser to catch said vortex spray, butnot said axial jet, said diffuser opening into an annular pressureplenum.
 50. A fountain as claimed in claim 49, in which said plenum isprovided with discrete nozzle exits.
 51. (canceled)
 52. A fountaindisplay as claimed in claim 35, wherein one or more of said displayelements comprises a fountain comprising: a supply of water underpressure; a primary fluidic diverter having an input for said supply,and first and second outputs diverging from said input, two controlports provided with control flow to direct input flow to one or other ofsaid outputs; and a vortex amplifier comprising a vortex chamber, aradial port, a vortex inducing port and an axial output port; whereinone of said first and second primary diverter outputs is connected tosaid vortex inducing port and the other is connected to said radialport, said axial port leading to a nozzle whereby an alternating vortexspray or axial jet is produced.
 53. A fountain display as claimed inclaim 52, in which said control ports are interconnected by an inertialoop, whereby oscillations are induced in the control flow to switchflow alternately between said first and second outputs.
 54. A fountaindisplay as claimed in claim 52, wherein two of said vortex amplifiersare provided in parallel, each with its own supply to its radial port,each vortex inducing port being connected to one or other of said firstand second outputs of the primary diverter.
 55. A fountain display asclaimed in claim 52, wherein two of said primary diverters are providedwhose first outputs are joined together and comprise the radial inputfor said vortex amplifier, and whose second outputs are connected toseparate vortex inducing ports of said vortex amplifier, whereby severalmodes of operation of the vortex amplifier results.